Cable pull adjustment for a parking brake

ABSTRACT

The invention relates to a device for adjusting a cable pull for parking brakes, comprising a first actuation lever ( 1 ) that can be rotated about a first axis (A 1 ), a notched ( 7   a ) pull element ( 3 ) that is spring-loaded in the direction of actuation of the cable pull, and a latching element ( 5 ) provided with a latch ( 5   a ). Said latch ( 5   a ) of the latching element ( 5 ) releasably engages with the notches ( 7   a ) of the pull element ( 3 ). The pull element ( 3 ) is mounted so as to be swiveled about a second axis (A 2 ) and comprises a notched ( 7   a ) pull rod ( 7 ) and a guide housing ( 6 ). The swiveled bearing of the pull element ( 3 ) about the second axis (A 2 ) is disposed on the guide housing ( 6 ). The invention provides a device for adjusting the cable pull of parking brakes that is inexpensive in production, ensures a long and reliable operation and is insensitive to soiling. The invention is characterized in that a force acting in the direction of the cable pull produces a torque of the pull element ( 3 ) with respect to the second axis (A 2 ) that is proportional to said force. The latching element ( 5 ) is swivelably mounted relative to the guide housing ( 6 ).

[0001] The invention relates to a device for adjusting a cable pull for parking brakes in accordance with the precharacterizing clause of claim 1.

[0002] Modern automobile construction makes increasing use of parking brakes which are actuated by a cable pull, including manually actuated and foot-actuated parking brakes, in which maintenance-free operation is ensured as far as possible over the entire service life of the motor vehicle by means of an automatic cable pull adjustment.

[0003] WO 98 578 32 describes a cable pull adjustment for parking brakes, in which a clamping element and a pull rod are guided movably in a clamping housing, a ratchet mechanism which is situated between the pull rod and the clamping element being brought into engagement on the clamping housing via a wedge guide. In an arrangement of this type, the clamping element and the pull rod are guided in a sliding manner, with friction occurring over a large surface area on both parts. A contact pressure, which is used for securing purposes, in the ratchet mechanism is brought about by the clamping element sliding over a wedge guide, with friction likewise occurring. Soiling which inevitably occurs during a service life of many years due to particles penetrating from the outside or else due to abrasion may cause the device to jam.

[0004] DE 297 21.843 U1 describes a cable pull adjustment for parking brakes, in which a pull rod which is provided with notches is fixed on a guide housing by means of a slot-shaped recess, with a locking element which interacts with the notches being formed on the guide housing. A guide pin reaches through the slot-shaped recess and secures the pull rod on the guide housing in such a manner that the pull rod is held in a manner such that it can be displaced longitudinally and also tilted about the guide pin with respect to the guide housing, a spring supporting the pull rod against the guide housing. A pull cable for actuating a brake is fixed to the pull rod.

[0005] It is the object of the invention to specify a device for adjusting a cable pull for parking brakes, which can be produced cost-effectively, ensures long and reliable operation and is not susceptible to soiling.

[0006] The invention achieves this object by means of a device mentioned at the beginning having the characterizing features of claim 1.

[0007] A device according to the invention advantageously has a pull element which is mounted pivotably and is moved toward a locking element by means of pivoting caused by the cable pull being tensioned. The engagement of latches provided on the locking element in notches provided on the pull element is therefore reinforced with increasing tensioning of the cable pull, as a result of which high operational reliability is ensured.

[0008] The pull element advantageously comprises a pull rod which is held in a guide housing and on which the notches of the pull element are formed. The design enables the pull rod to have a sufficient amount of play in the guide housing and to have a relatively small surface area guided with friction, with the result that jamming due to soiling or abrasion can be virtually eliminated.

[0009] In order to ensure engagement of the locking element with the pull element even if the cable pull is not tensioned, a pre-loading spring is advantageously provided which is supported on one side against the guide housing and on the other side against the locking element.

[0010] In a preferred embodiment of the device according to the invention, the locking element is mounted in a manner such that it can pivot about the same axis as the pull element, as a result of which possible jamming of the device is eliminated to a particular extent.

[0011] The cable pull adjustment is advantageously brought about via an adjusting spring which supports the pull rod against the guide housing in a longitudinal direction of the pull rod, which contributes to a particularly compact construction of the device according to the invention.

[0012] A stop is particularly advantageously provided and is used to prevent engagement of the locking element with the pull element in a normal position of the actuating lever, with the result that malfunctions of the cable pull adjustment, for example due to the cable pull becoming stuck e.g. by freezing in winter, are avoided.

[0013] In order to permit simple and rapid installation of the parking brake, a ball cage is advantageously articulated in a pivotable manner at one end of the pull element, it being possible for that end of a pull cable which is provided with a ball-like thickened section to be inserted with simple movement into said ball cage, with it being fixed in the ball cage by the pull cable being pulled back.

[0014] Further advantages and features of the invention emerge from the exemplary embodiment described below and from the dependent claims.

[0015] The invention will be explained in greater detail below with reference to a preferred exemplary embodiment of the invention using the attached drawings.

[0016]FIG. 1 shows a side view of a device according to the invention.

[0017]FIG. 2 shows an exploded drawing according to FIG. 1.

[0018] As can be seen from FIG. 1, the parking brake illustrated in the present exemplary embodiment is a foot-operated parking brake which comprises an actuating lever 1 which can be rotated about a first axis A1 by means of a lever bearing 1 d. The actuating lever 1 is designed in two parts, a pedal part 1 a and a ratchet part 1 b being fixed to each other. A locking element 5 and a pull element 3 are fixed on the actuating lever 1 in a manner such that they can pivot about a second axis A2 in a rotary joint 4.

[0019] As is apparent in particular from FIG. 2, the rotary joint 4 comprises a hole 4 a on the ratchet part 1 b of the actuating lever 1 and a graduated rivet 4 b. The locking element 5 comprises a latch part 5 a and a lever part 5 b. This is advantageous since the latch part 5 a is expediently manufactured from a hard material, whereas the lever part 5 b is a shaped part of complicated shaping made from simple sheet metal. The pull element 3 comprises a guide housing 6, which is composed of two sheet-metal shaped parts 6 a and 6 b, and a pull rod 7 on which notches 7 a are formed. The pull rod 7 is enveloped by an adjusting spring 8 which supports the pull rod 7 in its longitudinal direction against the guide housing 6. The locking element 5 is supported against the pull element 3 by a torque produced by means of a pre-loading spring 9, the pre-loading spring 9 being held by a pin 9 a which is fixed on the guide housing 6 of the pull element 3. A ball cage 10 is fixed pivotably to one end of the pull rod 7 of the pull element 3 and into it is placed the end of a cable 11 (see FIG. 1) which belongs to the cable pull (not illustrated more specifically) of the parking brake.

[0020] Furthermore, a stop 12 which is fixed on the bodywork is provided (see FIG. 1).

[0021] The invention operates as follows:

[0022] In a normal position of the actuating lever 1, the stop 12 which is fixed on the bodywork engages on the locking element 5, with the result that the latch part 5 a and the notches 7 a of the pull rod 7 are not engaged. If the actuating lever 1 is actuated, it is rotated anticlockwise about the first axis A1. Even after a few degrees of rotation the stop 12 no longer engages on the locking element 5, with the result that the locking element 5 and the pull element 3 are brought into engagement with each other by means of the prestressing spring 9. In this state, the pull rod 7, which is correspondingly pushed forward by the adjusting spring 8, causes the cable 11 to be in a pretensioned position in which there is no play in the cable 11. As actuation of the parking brake continues, the tension of the cable 11 increases, with the position of the pull rod 7 in the guide housing 6 of the pull element 3 being fixed by the engagement of the locking element 5 in the notches 7 a. Owing to the fact that the pulling direction of the cable 11 and the central point of the rotary joint 4 are not in line, torque is produced in the rotary joint 4 that is proportional in its magnitude to the tensile force of the cable 11 and therefore presses the latch part 5 a of the locking element 5 against the notches 7 a of the pull rod 7 as the force increases. This ensures that, even with large tensile forces of the cable 11, the pull rod 7 of the pull element 3 remains arrested in its position.

[0023] The arresting of the parking brake in its actuated position takes place in a known manner via a ratchet toothing 1 c, which is formed here on the ratchet part 1 b of the actuating lever 1. This shows the advantage of a two-part construction of the actuating lever 1, since a ratchet toothing 1 c of this type preferably consists of a harder material than is necessary for the lever part 1 a of the actuating lever 1.

[0024] In an unfavorable case, for example due to severe frost in winter, the cable may become stuck in the arrested position of the parking brake. The following release and resetting of the actuating lever 1 of the parking brake into a normal position by a spring (not illustrated) would therefore result, in accordance with the action of the adjusting spring 8, in the pull rod 7 being extended by the maximum possible adjustment travel of the cable pull adjustment. A misadjustment caused in this manner of the cable pull adjustment may render complete release of the brake impossible. So that a correct adjustment of the cable pull can be restored even in the event of a process described above, a stop 12 is provided which is fixed on the bodywork and engages on the lever part 5 b of the locking element 5 in the normal position of the actuating lever 1, with the result that the latch part 5 a of the locking element 5 is disengaged from the notches 7 a of the pull rod 7, so that the pull rod 7 is freely moveable in its guide housing 6. A subsequent release of the stuck pull cable 11 then leads again to the device according to the invention being set for operation by means of a brake-resetting means which is provided in a known manner. 

1. A device for adjusting a cable pull for a parking brake, comprising an actuating lever (1) which can be rotated about a first axis (A1), a pull element (3) which is provided with notches (7) and is spring-loaded in an actuating direction of the cable pull, a locking element (5) which is provided with a latch part (5 a), the latch part (5 a) of the locking element engaging releasably in the notches (7 a) of the pull element (3), the pull element (3) being pivotally mounted about a second axis (A2), and the pull element (3) comprising a pull rod (7), which is provided with notches (7 a), and a guide housing (6), the pivotally mounting of the pull element (3) about the second axis (A2) being provided on the guide housing (6), characterized in that a force acting in the direction of the cable pull causes a torque of he pull element (3) with respect to the second axis (A2) that is proportional to the force, and in that that locking element (5) is mounted pivotally with respect to the guide housing (6).
 2. The device according to in claim 1, characterized in that the spring loading which is directed in the actuating direction of the cable pull is imparted by an adjusting spring (8) which supports the guide housing (6) against the pull rod (7) in a longitudinal direction of the pull rod (7).
 3. The device according to claim 1, characterized in that the locking element (5) is arranged in a manner such that it can pivot about the second axis (A2).
 4. The device according to claim 1, characterized in that the locking element (5) comprises a latch part (5 a) and a lever part (5 b).
 5. The device according to claim 1, characterized in that a pre-loading spring (9) is provided which is supported on one side against the guide housing (6) and on the other side against the locking element (5).
 6. The device according to claim 1, characterized in that a stop (12) which is fixed on the bodywork is provided, the stop (12) engaging on the locking element (5) in a normal position of the actuating lever (1), and the locking element (5) and the pull element (3) being prevented from being engaged by means of the stop (12) in the normal position of the actuating lever (1).
 7. The device according to claim 1, characterized in that a retainer (10) for a cable (11) of the cable pull is provided on the pull element (3).
 8. The device according to claim 7, characterized in that the retainer for the cable (11) is formed by a ball cage (10) which is arranged pivotably on the pull element (3). 